Comments on: Industrial Strength Voodoo Correlationshttps://climateaudit.org/2009/01/16/another-interesting-mann-puzzle/
by Steve McIntyreMon, 19 Mar 2018 14:06:25 +0000hourly1http://wordpress.com/By: Deep Climatehttps://climateaudit.org/2009/01/16/another-interesting-mann-puzzle/#comment-172909
Wed, 21 Jan 2009 03:26:47 +0000http://www.climateaudit.org/?p=4855#comment-172909More generally, perhaps the CPS reconstruction would benefit from a screening procedure that would weed out the proxies with correlations that fluctuate wildly over the instrumental period (e.g. specify a maximum difference in r between the first half and second half of the calibration period as an additional screening criterion).
]]>By: Deep Climatehttps://climateaudit.org/2009/01/16/another-interesting-mann-puzzle/#comment-172908
Tue, 20 Jan 2009 20:46:03 +0000http://www.climateaudit.org/?p=4855#comment-172908Here are some initial thoughts about the “opportunistic” use of the Socotra dO18 proxy. It does seem to me that the greatly varying correlation of this proxy, depending on the period chosen, could argue against its inclusion in paleoclimate reconstruction.

But what would be the implication of its exclusion for validation? To me, it seems that removal of the proxy would improve the validation scores, at least for the 1950-1995 recon. Why? Well, since the overall correlation is strongly positive, it is likely that the correlation in the 1949-1995 period was also positive. But as Steve has noted, in that reconstruction, the proxy was used in a negative orientation based on 1850-1949 calibration.

Out of 1209 proxies, 308 have opposite “low frequency” orientations between early-miss and late-miss. Presumably many are “significant” in both directions.

Strictly speaking, the Socotra d018 is the only proxy passing the significance test for all three periods and having an opposing sign between the “late miss” and “early miss” periods. But most of the proxies (tree ring, coral etc.) are evaluated with a one-sided test, so this is not a surprising result.

Of the 484 proxies passing the 1850-1995 significance test, 342 also passed both sub-period tests (with 341 having r values with matching sign). 111 passed only one of the sub-period tests, and 31 failed both sub-periods.

]]>By: Deep Climatehttps://climateaudit.org/2009/01/16/another-interesting-mann-puzzle/#comment-172906
Tue, 20 Jan 2009 20:15:17 +0000http://www.climateaudit.org/?p=4855#comment-172906There seems to be some confusion among readers about this post. So I believe the following graph is a useful aid (and could even be usefully incorporated into the original post).

Essentially Steve is discussing the validation procedure in Mann et al 2008, presumably the NH CPS reconstruction for period 1950-1995 (last part of graph), which in turn is based on proxy calibration to instrumental temperature in the period 1850-1949 (“late miss” in Steve’s terminology).

SD1.xls contains the “passing” values of r of each proxy for the three periods (1850-1995, 1896-1995, 1850-1949). The 1950-1995 reconstruction is based on the proxies found to be significant in the 1850-1949 period.

]]>By: Mark T.https://climateaudit.org/2009/01/16/another-interesting-mann-puzzle/#comment-172905
Tue, 20 Jan 2009 16:10:43 +0000http://www.climateaudit.org/?p=4855#comment-172905Isn’t the point of a blog, or at least one of the points, to elicit relevant comments from readers? Maybe a thought is stuck and needs some prodding from the masses to complete it?

RC’s reaction should be interesting if they say anything. Since I can’t even comment there after asking them politely to rationalize removing data by correlation — RC gave a big SNIP to that question. I had no understanding of how over the top those guys were at the time or the question would never have been asked. It’s just data folks!

Maybe a post on some of the early RC comments and some from the paper contrasted with reality would be fun on The Air Vent. I’m still waiting patiently for the detail from Steve’s latest quantum multi-state anti-proxy discovery though.

]]>By: braddleshttps://climateaudit.org/2009/01/16/another-interesting-mann-puzzle/#comment-172900
Sun, 18 Jan 2009 21:34:55 +0000http://www.climateaudit.org/?p=4855#comment-172900Don’t get me wrong, I am a great admirer of this blog and read it every day, but this post is a great example of why this blog has less influence than it should. The opening sentence, as PaulM mentions, would be baffling to an outside reader, who may not read on, and the main finding, which seems quite dramatic to me, is found in the comments (#5) not in the blog entry itself.

I suspect that the principals on the other side of the debate will be happy to ignore this unless something serious is done to publicise it, and nothing will come of it.